The present invention relates to a method and to a booster which are intended to detect the braking of a vehicle, and also to a method of producing such a booster.
A vehicle braking device 100 (FIG. 1) is generally operated by a driver using a brake pedal 102 intended to transmit the command force f exerted on this pedal 102 to a braking system 113 comprising, for example, a caliper equipped with a piston and with brake pads which are intended to clamp a disk secured to a braked wheel.
To amplify the force f exerted by this driver into a force F transmitted to the braking system, it is known practice to use a pneumatic brake booster 104.
To that end, this booster 104 comprises a casing 106 cooperating with a control rod 108, connected to the brake pedal 102, and with a push rod 110 connected to a master cylinder 112 connected to the braking system 113, such that when the control rod 108 is moved by means of an action f transmitted by the brake pedal 102, the booster 104 moves the rod 110 with a thrust F whose intensity is greater than the intensity of the command f.
To achieve this, the casing 106 comprises a cover 114 and a cylinder 116 cooperating with this cover 114 in a sealed manner, the internal volume of the casing 106 then being divided into a first chamber 118, termed rear chamber, and into a second chamber 120, termed front chamber, by means of a rigid skirt 122 and a flexible diaphragm 124 which provide sealing between these two chambers 118 and 120.
In a first instance, when the booster 104 is inactive, that is to say when no braking action is applied by the driver of the vehicle, the pressure in the rear 118 and front 120 chambers is kept below the atmospheric pressure by means of a pumping device (not shown).
In a second instance, when the driver of the vehicle presses on the brake pedal 102, the control rod 108 moves under the action of the command f and activates a pneumatic mechanism 126 such that air at atmospheric pressure enters the rear chamber 118.
Since the pressure in the rear chamber 118 is higher than the pressure in the front chamber 120, the diaphragm 124 and the skirt 122 are subjected to a thrust F whose intensity is equal to ΔP×S, where ΔP is the difference in pressure between the two chambers and S is the area of the diaphragm.
The movement of the skirt 122, and of the associated rod 110, thus transmits a thrust F to the master cylinder 112 associated with the braking system.
Moreover, the detection of a braking action is an essential operation in a vehicle, for example in order to generate a signal intended to illuminate brake lights at the rear of the vehicle, thus indicating the start of braking to other vehicles, or in order to activate various electronic systems associated with braking, such as the antilock system (ABS).
Such a detection currently uses a sensor 128 which senses the movement of the brake pedal 102, this sensor comprising a first fixed connector 130a and a second movable connector 130b which can move on the pedal such that this second connector comes into contact with the first, closing an electric circuit, when the driver presses on the brake pedal 102.